The president not only wants to cut missiles, he also is neglecting a promised modernization program.

By BOB CORKER AND JIM INHOFE

President Obama has repeatedly identified nuclear proliferation and nuclear terrorism as key dangers to the United States and its allies. His analysis is correct, but that cannot be said about the centerpiece of his response: declaring America's commitment to eliminate its own nuclear weapons on the way to a world of "nuclear zero." Meanwhile, he has neglected to modernize the weapons that are essential to American security.

The president's approach is mistaken. Nothing demonstrates the hollowness of the disarmament dream as clearly as the international community's inability to keep regimes such as North Korea—and soon Iran—from acquiring nuclear weapons. The recent North Korean nuclear test clearly and dangerously demonstrated how little regard rogue states hold for a nuclear-armed U.S. Why would they be more intimidated, much less moved to disarm themselves, by an America that was whittling away its own nuclear superiority?

If anything, reducing the American arsenal is likely to cause the very instability that the U.S. seeks to avoid. Without an American commitment to a strong nuclear deterrent, the country's friends and allies could develop doubts about where the U.S. stands and what it would do to safeguard its own interests and theirs.

Many other nations depend on U.S. nuclear-security assurances and could come to question whether further reductions in the U.S. nuclear arsenal—and an American political leadership that prizes disarmament posturing over the hard work of counter-proliferation—can credibly protect them against proliferators and other threats.

If these friends doubt U.S. capability and resolve, they may feel the need to develop their own nuclear weapons. Moreover, some potential adversaries, as America rushes to disarm, may be encouraged to acquire or expand nuclear arsenals, seeking to become nuclear "peers."

The commitment to modernizing America's nuclear deterrent appeared to be well established before the vote on the New Start Treaty with Russia in December 2010. In fact, the president's own 2010 Nuclear Posture Review states clearly that nuclear reductions depend on a modernized and responsive nuclear infrastructure. The president assured the Senate of his intent to modernize or replace the strategic "nuclear triad" (intercontinental ballistic missiles, submarine-launched ballistic missiles and nuclear-armed bombers), while specific funding targets, over 10 years, were established to rebuild a nuclear infrastructure that dates back to the dawn of the nuclear age. Regrettably, that commitment seems to have dissipated.

Funding for the nuclear weapons complex is now $770 million short of what was promised to date. A vital plutonium-handling facility—deemed essential even by the president until last year and to be built at Los Alamos National Laboratory in New Mexico—has been deferred by at least five years, which probably means never.

It's likely that additional cutbacks will appear in the fiscal-year 2014 budget request. Indeed, virtually all nuclear-modernization programs are now delayed by at least two years or, in the case of a new ICBM, have yet to be announced.

Putting aside the many recent setbacks to the U.S. relationship with Russia, it seems unlikely that Moscow will agree to any further nuclear reductions without concomitant limitations on American missile-defense capabilities—a demand that will be a clear nonstarter for the U.S. Senate. As a result, such negotiations are likely to increase friction between the two countries. A far better approach would be to move beyond the obsession with numerical reductions and instead focus on improving nuclear transparency and on ensuring stability during crises—and not just for the U.S. and Russia, but for all nuclear powers.

To be clear, until the U.S. has a modern and responsive nuclear infrastructure—one capable of responding to any future challenges to the country's strategic interests—no arms-control treaty is likely even to get a vote in the Senate. A presidential attempt to circumvent Congress by pursuing reductions unilaterally would be counter to the advice of the secretary of defense and the chairman of the Joint Chiefs of Staff and would be met with stiff resistance on Capitol Hill.

The president has a choice: running into a likely stalemate on nuclear disarmament or working with Congress on practical and realistic steps to stop nuclear proliferation and improve nuclear security.

Sen. Corker (R., Tenn.) is the ranking member of the Senate Foreign Relations Committee. Sen. Inhofe (R., Okla.) is the ranking member of the Senate Armed Services Committee.

A version of this article appeared Feb. 26, 2013, on page A15 in some U.S. editions of The Wall Street Journal, with the headline: 'Nuclear Zero' Offers Nothing Worth Having.